CN111794030A - The method of widening the embankment foundation at the building through the embankment - Google Patents

Abstract

The method for widening the embankment foundation at the building that crosses the embankment according to the present invention includes the following steps: base treatment: excavating the leeward side slope of the existing embankment, and laying the anti-seepage geomembrane along the excavation step; The second layer and the penultimate layer of the soil are covered with steel wire mesh. The steel wire mesh is welded by steel wire. The outer side of the foam light soil is set with a cohesive soil edging, and the top of the foam light soil is lapped with concrete slabs. The three-way geogrid is fully paved below the layer. Pavement structural layers are laid on concrete slabs. The invention is a technology suitable for adopting a new type of widening roadbed treatment where there are structures crossing the embankment, which can effectively reduce the impact of the widening roadbed on the existing buildings crossing the embankment, meet the engineering needs of a specific road section, and provide a feasible implementation. scheme to provide support for the entire width of the subgrade.

Description

The method of widening the embankment foundation at the building through the embankment

technical field

The invention relates to the field of road and embankment engineering, in particular to a method for widening embankment foundations at buildings crossing the embankment; it is a processing technology for using foam light soil to widen embankment roads and combine to form roadbeds.

Background technique

With the development of the country and the improvement of people's living standards, people's demand for water is getting higher and higher. The riverside, riverside and lakeside cities are all developing and utilizing the shoreline comprehensively, making the beach, embankment, road and shore into a The idea of overall construction is being gradually promoted. In many projects, in order to improve the overall effect and realize the unified coordination of multiple functions, it is usually necessary to widen and increase the existing embankment. However, due to various functional requirements, there are some structures (such as pipelines or tunnels) that penetrate the embankment under the existing embankment. The use of general backfill materials and rolling methods in the joint section of embankment and road will have a great impact on the existing buildings passing through the embankment, and even some sections will affect the feasibility of the scheme. Therefore, for similar road sections, a new type of widened embankment is urgently needed. base processing technology.

At present, due to the connection of majors involving water conservancy, transportation, and construction, there are few studies and reports on the treatment of widened embankment foundations in this area, and relevant technical guidance is also lacking in relevant specifications. Therefore, it is very necessary to explore a technology of widening the roadbed at the crossing structure.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to provide a method for widening the embankment foundation at the crossing of the embankment building. From the perspectives of engineering safety, technical feasibility, construction convenience, engineering investment, etc., the invention reduces the influence of widening the roadbed on the existing embankment-piercing buildings, and meets the needs of widening the embankment foundation at the embankment-piercing buildings.

The object of the present invention is achieved through the following measures: the method for widening the embankment foundation at the building through the embankment is characterized by comprising the following steps:

The first step, base treatment: After the original foundation is treated, a 0.5m thick cohesive soil cushion is set up. The cohesive soil is mixed with 12% cement by weight, and it is leveled and compacted, and the compaction degree of the base is not less than 90%. ;

The second step is to excavate the slope of the current leeward side of the embankment, and the steps are inclined inward by 2% to 4%; the height of the steps is consistent with the filling height of each layer of foam light soil;

Step 3: Fully lay anti-seepage geomembrane along the excavation steps to reduce the impact of the embankment on the newly filled foam light soil;

Step 4: Add steel wire mesh to the second layer and the penultimate layer of the foam light soil to enhance the ability of the foam light soil to bear the vehicle load; 100mm;

Step 5. In order to avoid the direct exposure of the foam light soil, set a cohesive soil edging on the outer side of the foam light soil, the thickness of which is not less than 1.0m, and the cohesive soil filler should meet the filling index requirements of roads and embankments;

Step 6. In order to facilitate the construction of the pavement structure layer and improve the anti-cracking function of the foam lightweight soil, the top of the foam lightweight soil is lapped with concrete slabs, and the three-way geogrid is fully covered below the pavement layer to reduce unevenness. The effect of settlement on the roadbed.

Step 7: Pavement structure layer paving on concrete slab.

In the above technical solution, the compressive strength of the foamed lightweight soil is ≥0.6MPa when the distance from the top surface of the roadbed exceeds 0.8m; when the distance from the top surface of the roadbed is less than 0.8m, the compressive strength is ≥0.8 MPa.

In the above technical solution, the thickness of the anti-seepage geomembrane is not less than 0.5mm, the longitudinal and transverse tensile strength is not less than 6kN/m, the CBR burst strength is not less than 2.5kN, and the hydrostatic pressure resistance is not less than 0.7MPa.

In the above technical solution, the cohesive soil is a cohesive soil with a clay content of 20% to 35% and a plasticity index of 15 to 20, and the permeability coefficient is controlled to be less than i×10 ^-5 cm/s, where i is 1 A positive integer up to 9.

In the above technical solution, the ultimate tensile strength of the three-way geogrid is not less than 50kN/m, and the tensile strength at 2% elongation is not less than 20kN/m; the three-way geogrid is anchored by U-shaped nails , U-shaped nail spacing 1m.

The invention is a technology suitable for adopting a new type of widening roadbed treatment where there are structures crossing the embankment, which can effectively reduce the impact of the widening roadbed on the existing buildings crossing the embankment, meet the engineering needs of a specific road section, and provide a feasible implementation. scheme to provide support for the entire width of the subgrade.

Description of drawings

FIG. 1 is a schematic structural diagram of the method of the present invention.

In the figure, 1. Proposed road, 2. Pavement structure layer, 3. Existing embankment, 4. Three-way geogrid, 5. Concrete slab, 6. Cohesive soil edging, 7. Steel wire mesh (or metal mesh) ), 8. Foamed lightweight soil, 9. Anti-seepage geomembrane, 10. Cement soil cushion, 11. Original ground, 12. Excavation steps, 13. Existing structures through embankment.

Detailed ways

The implementation of the present invention will be described in detail below with reference to the accompanying drawings, but they do not constitute a limitation of the present invention, but are merely examples. At the same time, the advantages of the present invention are made clearer and easier to understand by the description.

Referring to accompanying drawing 1, the method for widening the embankment foundation of the present invention at the place where the embankment is constructed is characterized in that it comprises the following steps:

The first step, base treatment: after the undisturbed foundation is treated, a 0.5m thick cohesive soil cushion is set up. The cohesive soil is mixed with 12% cement by weight, and it is leveled and compacted, and the base compaction degree is not less than 90%. ;

The second step is to excavate steps on the backwater side slope of the existing embankment, and the steps are inclined inward by 2% to 4%; the height of the steps is consistent with the filling height of each layer of foam light soil;

The third step is to spread the anti-seepage geomembrane along the excavation steps to reduce the impact of the embankment on the newly filled foam light soil;

Step 4: Add steel wire mesh to the second layer and the penultimate layer of the foam lightweight soil to enhance the ability of the foam lightweight soil to bear the vehicle load; 100mm;

In the fifth step, in order to avoid the direct exposure of the foam lightweight soil, a cohesive soil edging is set on the outer side of the foam lightweight soil, and its thickness is not less than 1.0m, and the cohesive soil filler should meet the filling index requirements of roads and embankments;

In the sixth step, in order to facilitate the construction of the pavement structural layer and improve the anti-cracking function of the foam lightweight soil, the top of the foam lightweight soil is lapped with concrete slabs, and the three-way geogrid is fully covered below the pavement layer to reduce unevenness. The effect of settlement on the roadbed.

Step 7: Pavement structural layer laying on the concrete slab.

When the foam lightweight soil is used in the range of more than 0.8m from the top surface of the roadbed, the compressive strength is ≥ 0.6MPa; when the distance from the top surface of the roadbed is less than 0.8m, the compressive strength is ≥0.8MPa.

The thickness of the anti-seepage geomembrane is not less than 0.5mm, the longitudinal and transverse tensile strength is not less than 6kN/m, the CBR burst strength is not less than 2.5kN, and the hydrostatic pressure resistance is not less than 0.7MPa.

The cohesive soil is a cohesive soil with a clay content of 20% to 35% and a plasticity index of 15 to 20, and the permeability coefficient is controlled to be less than i×10 ^-5 cm/s.

The ultimate tensile strength of the three-way geogrid is not less than 50kN/m, and the tensile strength at 2% elongation is not less than 20kN/m; the three-way geogrid is anchored with U-shaped nails, and the spacing between the U-shaped nails is 1m .

The structure of the present invention to widen the embankment foundation at the building through the embankment: including the existing embankment 4, the existing through building 13, and the proposed road 1, and the proposed road 1 includes the opening on the backside slope of the existing embankment 4. The excavation step 12, the anti-seepage geomembrane 9 fully laid along the excavation step 12, the cement-soil cushion 10 on the original foundation, the foam light soil 8 on the cement-soil cushion 10, and the foam light The second layer and the penultimate layer of the soil have steel wire mesh 7, and the top of the foam light soil 8 is lapped with a concrete slab 5, and a three-way geogrid is fully covered between the pavement structural layer 2 and the concrete slab 5. 4. A cohesive soil edge 6 is arranged on the outer side of the foam light soil. Excavation steps 12 are arranged at intervals on the outside of the foam lightweight soil.

The detailed construction process requirements of the present invention to widen the embankment foundation technology at the embankment building place are as follows:

(1) According to the construction mix ratio, the cast-in-place foam light soil shall be prepared for use. When used for the foam light soil with a distance of more than 0.8m from the top surface of the roadbed, the compressive strength is ≥0.6MPa; when the distance from the top surface of the roadbed is less than 0.8 MPa Foamed lightweight soil in the m range, compressive strength ≥ 0.8MPa.

(2) A standard stepped platform shall be excavated on the backwater slope of the original embankment, and the width of the platform should not be less than 1.0m; when multiple steps are set, the height of a single step should be 0.5m to 1.0m. Lay a layer of anti-seepage geomembrane along the steps, using PE material, the thickness is not less than 0.5mm, the longitudinal and transverse tensile strength is not less than 6kN/m, the CBR burst strength is not less than 2.5kN, and the hydrostatic pressure resistance is not less than 0.7MPa.

(3) Clean the topsoil in the widening range of the embankment, then backfill with cohesive soil mixed with cement, level and compact it, and the compaction degree of the base is not less than 90%.

(4), pouring foam light soil. The top surface area of a single pouring area shall not exceed 400m ² , and it shall be divided into a section every 20m along the longitudinal length of the road. The pouring height is divided according to the height of the subgrade, the thickness of a single layer is 0.5m to 1.0m, and the thickness of each layer should be consistent with the thickness of the steps at the joint; the subgrade part is poured in two layers with a thickness of 0.4m. The interface of the pouring layer is the location of the metal mesh. After each layer is poured, plastic film or anti-seepage geomembrane should be used for covering and moisturizing maintenance.

(5), deformation seam setting. Except for special circumstances, the foam lightweight soil shall be arranged with a horizontal deformation seam every 20m and a width of 2cm, and the classification shall be filled with waterproof materials.

(6), metal mesh construction. Wire mesh is installed at the bottom and top of the foam light soil filling body. The width of the steel mesh and the foam light soil filling is the same, and U-shaped nails are used for anchoring. The spacing between the U-shaped nails is 1m and is arranged in a plum blossom shape.

(7), cover with anti-seepage geomembrane. The foam lightweight soil should be covered and maintained within seven days after the construction is completed, and then the anti-seepage geomembrane should be laid.

(8), edging soil filling. Use cohesive soil for filling, and the cohesive soil filler adopts cohesive soil with a clay content of 20% to 35% and a plasticity index of 15 to 20, and the permeability coefficient is controlled to be less than i×10 ^-5 cm/s.

(9), the top concrete slab construction. After the foam light soil is filled to the design elevation and the maintenance is completed, in order to facilitate the construction of the pavement structure, a 15cm thick C15 concrete slab is poured on the top surface.

(10), laying three-way geogrid. Below the pavement structure layer of the widened subgrade, three-way geogrid is laid on the top concrete slab in the eighth step, and its ultimate tensile strength is not less than 50kN/m, and the tensile strength at 2% elongation is not less than 20kN/ m. The three-way geogrid is anchored with U-shaped nails, and the spacing of the U-shaped nails is 1m, which is arranged in a plum blossom shape.

(11) Pavement structure layer, pavement structure layer shall be paved according to the pavement structure required by the design document.

The terms of the positional relationship described in the present invention are only descriptions for the corresponding drawings pointed to, and do not limit the positional relationship thereof.

Other unexplained parts belong to the prior art.

Claims (5)

1. the method for widening the embankment foundation at the place of passing through the embankment building is characterized in that comprising the following steps: The first step, base treatment: After the original foundation is treated, a 0.5m thick cohesive soil cushion is set up. The cohesive soil is mixed with 12% cement by weight, and it is leveled and compacted, and the compaction degree of the base is not less than 90%. ; The second step is to excavate the slope of the current leeward side of the embankment, and the steps are inclined inward by 2% to 4%; the height of the steps is the same as the filling height of each layer of foam light soil; Step 3: Cover the anti-seepage geomembrane along the excavation steps; Step 4: Add steel wire mesh to the second layer and the penultimate layer of the foam light soil. Step 5. Set a cohesive soil edging on the outside of the foam light soil, and its thickness is not less than 1.0m. The cohesive soil filler should meet the filling index requirements of roads and embankments. Step 6: Concrete slabs are lapped on top of the foam lightweight soil, and a three-way geogrid is fully paved below the pavement layer. Step 7: Pavement structure layer paving on concrete slab. 2 . The method for widening the embankment foundation at the building passing through the embankment according to claim 1 , wherein the compressive strength is ≥0.6 when the foamed lightweight soil is used in a range exceeding 0.8 m from the top surface of the roadbed. 3 . MPa; when used in the range of less than 0.8m from the top surface of the roadbed, the compressive strength is ≥0.8MPa. 3. The method for widening the embankment foundation at the building crossing the embankment according to claim 1, wherein the thickness of the anti-seepage geomembrane is not less than 0.5mm, and the longitudinal and transverse tensile strength is not less than 6kN/m, The burst strength of CBR is not less than 2.5kN, and the hydrostatic pressure resistance is not less than 0.7MPa. 4 . The method for widening the embankment foundation at the building crossing the embankment according to claim 1 , wherein the cohesive soil is made of clay with a clay content of 20% to 35% and a plasticity index of 15 to 20. 5 . For soil, the control permeability coefficient is less than i×10 ^-5 cm/s. 5 . The method for widening the embankment foundation at the building crossing the embankment according to claim 1 , wherein the ultimate tensile strength of the three-way geogrid is not less than 50kN/m and 2% elongation. 6 . The tensile strength is not less than 20kN/m; the three-way geogrid is anchored with U-shaped nails, and the spacing between the U-shaped nails is 1m.

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